Planar electrodes are used in a variety of applications including Coulter counters, supercapacitors, and high capacity batteries. In many applications the planar electrodes are in contact with an electrolyte. A layer of charge that collects on the planar electrode is matched by a layer of charge in the electrolyte. This combination of charge layers results in a capacitor commonly referred to as an electric double layer capacitor (EDLC). An example of a prior art EDLC is shown in FIG. 1.
In applications where planar electrodes are used to monitor presence of particles in the electrolyte or to measure the number and size of each particle as the particle is going by the electrodes, certain characteristics of the electrodes can play a significant role in the measurements. For example, capacitance of the EDLC can play a significant role in the accuracy of measurements.
In applications where charge storage is the objective of a capacitor, e.g., supercapacitors or batteries for electrical cars, maximizing the capacitance is an important goal. Supercapacitors differ from other commonly known capacitors in the amount of capacitance. Generally, supercapacitors have much larger capacitance by way of larger electrodes. Physical size constraints as well as mechanical constraints, however, prevent producing capacitors with excessively large plates (electrodes).
In both of the above applications, attempts have been made in the prior art to provide a porous structure for the electrodes. The porous structure provides a larger surface area and thereby a larger capacitance. Both carbon nanotube technology and platinum black electrodes have been shown to provide porous features that can be used to increase the EDLC. Both of these schemes, however, present challenges. For example, processing involved in fabricating platinum black electrodes is 1) not a full dry process and/or 2) does not result in a well controlled electrode material. Similarly, carbon nanotube growth does not provide a well controlled electrode material. Furthermore, neither of these solutions is well suited for mass production with commonplace semiconductor technology processing steps.
Therefore, a need exists to address the stated shortcomings of the prior art. Particularly, there is a need to provide mass production of planar electrodes having large surface areas using common semiconductor processing techniques that can result in a well controlled electrode material.